We have isolated a cDNA clone, pCA12-2, from a lambda gt11 cDNA library of an adriamycin-resistant subline of human myelogenous leukemia K562 (K562/ADM) by plaque hybridization with the 2.6 kb genomic probe of P-glycoprotein reported previously.
Amplification and increased expression of the mdr1 gene associated with multidrug resistance in human tumors were found in multidrug-resistant sublines of human myelogenous leukemia K562 selected with vincristine (K562/VCR) or adriamycin (K562/ADM).